Conventionally, an electrophotographic image forming apparatus such as a copying machine, a multifunction printer, a printer, and a facsimile has been known. The image forming apparatus forms an electrostatic latent image on a surface of a toner image bearing member (photoreceptor), develops the electrostatic latent image with the use of toner supplied from a developing device, and transfers and fixes thus obtained toner image onto a sheet such as paper.
In the image forming apparatus, a developer is stirred and circulated in the developing device so that a two-component developer (also referred to as developer) including toner and carrier are rubbed together and triboelectrically charged. At a developing stage, the toner thus triboelectrically charged moves, due to an electrostatic force, towards the electrostatic latent image formed on the toner image bearing member. Thus, a toner image is formed. Note that a developer contains toner of at least three colors in a color image forming apparatus.
Further, toner which can be fixed on a sheet at a relatively low temperature (toner having a lower melting point) has been developed in response to a demand in a market for improvement in energy conservation. However, in a small-sized image forming apparatus, toner is easily affected by heat from a heat source such as a fixing device. Therefore, in a case where toner having a lower melting point is used in such an image forming apparatus, it is more likely that aggregation and blocking of the toner occur. This causes deterioration in fluidity of the toner. Therefore, a toner-carrying performance is damaged in a small-sized image forming apparatus.
In order to solve this problem, techniques for securing the toner-carrying performance have been developed. For example, Patent Document 1 discloses a toner carrying device including a loosening member which is rotatably provided in a predetermined position of a toner carrying path leading up to a developing device and is configured to loose a soft blocking toner lump.